1. Technical Field
The present application relates to a technique of determining whether a speech sound has been aurally comprehended or not, and whether a speech sound has been heard in comfort. More specifically, the present application relates to a hearing determination system which simultaneously determines speech sound intelligibility and comfortableness, for the “fitting” of a hearing aid or the like to provide a sound of appropriate loudness for each individual user by adjusting the amount of amplification, etc., of sounds with respect to each frequency.
2. Description of the Related Art
In recent years, people suffering from presbycusis are increasing in number due to the aging society. Even among the young, due to increased opportunities for listening to loud music for long hours as well as other influences, there is an increasing number of people suffering from hypacusia associated with acoustic traumas. Moreover, due to the downsizing and improved performance of hearing aids, users feel less of a psychological barrier against wearing hearing aids. Against this background, there is an increasing number of users of hearing aids.
A hearing aid is a device for amplifying sounds of frequencies which are difficult for a user to aurally distinguish. The purpose of wearing a hearing aid is to provide an improved aural distinction ability in conversation by compensating for deteriorated hearing of a user. The amount of sound amplification which a user desires in a hearing aid varies depending on the level of deterioration in the hearing of the user. Therefore, before beginning use of a hearing aid, it is first necessary to conduct a hearing determination for each user.
Within the realm of hearing determination required prior to using a hearing aid, determination of speech sound intelligibility is of importance. “Determination of speech sound intelligibility” means a determination as to whether a speech sound has been aurally comprehended or not. Specifically, it pertains to a determination of an aural distinction ability as to whether a monosyllabic speech sound has been aurally comprehended or not. A “monosyllabic speech sound” is either a single vowel or a combination of a consonant and a vowel (e.g., “ (a)”/“ (da)”/“ (shi)”).
According to “HOCHOKI FITTINGU NO KANGAEKATA (or “Concept of Hearing Aid Fitting”), Kazuoki KODERA, Shindan To Chiryosha, 1999, p. 166), conventional determination of speech sound intelligibility has been performed through the following procedure. First, by using the 57S list (50 monosyllables) or the 67S list (20 monosyllables) proposed by the Japan Audiological Society, a user is allowed to hear monosyllabic audios, one by one, the audios being presented orally or by playing back a CD. Next, through oral explanation, writing, or other methods, the user is asked to answer which speech sound he or she has aurally comprehended the presented speech sound to be. Then, a person making the determination matches the answer against the list, and calculates a correctness rate, which is a rate of monosyllables that have been correctly aurally comprehended among all monosyllables. This correctness rate defines the speech sound intelligibility. As for methods of speech sound intelligibility determination, techniques described in Japanese Laid-Open Patent Publication No. 9-038069 and Japanese Laid-Open Patent Publication No. 6-114038 are known.